What fatigue failure is
Fatigue failure is a progressive cracking mechanism. Each time a link passes over a sprocket it is loaded and unloaded; a stress concentration at a plate hole or a sharp edge becomes a crack initiation site. The crack grows slowly, then the plate fractures at a load well below its tensile rating.
Common causes
- Continuous operation at or above the drive's rated fatigue strength
- Sharp corners, corrosion pits or stamping burrs acting as stress raisers
- Vibration and shock loading adding to the base load cycle
- Incorrect preload or excessive tension raising mean stress
Warning signs
- Single plate fractures with a smooth, crescent-shaped crack face and a rough final tear
- Failures that repeat at the same position in the run
- Cracks near pin holes that bright-light inspection reveals before breakage
- Chain life well short of the calculated design life
Prevention and correction
- Size the drive with a service factor for the true duty cycle
- Reduce shock through soft-start, torque limiting or resilient couplings
- Remove corrosion and mechanical damage to plate edges
- Schedule periodic crack inspection at known high-load positions
Fix it with the right product
Chain selector and sizing toolsNeed a second opinion?
Send us the chain, the running hours and a photo. Our engineers will confirm the failure mode and quote the right replacement.
All chain failure modes
Chain ElongationFatigue FailureSide Plate CrackingPin and Bush WearRoller Wear and SpallingAbrasive WearAdhesive WearCorrosionStress Corrosion CrackingHydrogen EmbrittlementGallingSurface PittingTensile OverloadShock LoadingImpact FractureLubrication StarvationTight Links and KinkingMisalignmentChordal ActionSprocket Tooth Wear
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Sheffield9 mi · ~25 min
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Wath-upon-Dearne4 mi · ~10 min
Wakefield20 mi · ~35 min
Leeds25 mi · ~45 min
Huddersfield30 mi · ~50 min
Scunthorpe22 mi · ~35 min
Mansfield28 mi · ~45 min
Chesterfield18 mi · ~30 min
Worksop14 mi · ~25 min